1. Field of the Invention
The present invention relates generally to the treatment of anatomical tissue with high intensity focused ultrasound energy and, more particularly, to focused ultrasound ablation devices having a plurality of selectively actuatable ultrasound emitting elements by which lesions of selected sizes and/or patterns are formed in anatomical tissue and to methods of thermal ablation using the same.
2. Brief Description of the Related Art
When high intensity ultrasound energy is applied to anatomical tissue, significant physiological effects may be produced in the anatomical tissue resulting from thermal and/or mechanical changes or effects in the tissue. Thermal effects include heating of the anatomical tissue; and, when the tissue is heated to a sufficiently high temperature, tissue damage such as coagulative necrosis is produced. Mechanical effects include liquefaction, cavitation and/or fragmentation of the anatomical tissue. In order to produce thermal effects in anatomical tissue, ultrasound treatment devices or applicators having ultrasound emitting members such as transducers have been used to emit ultrasound energy which is applied to anatomical tissue by positioning the ultrasound emitting members adjacent or in contact with the tissue or by coupling the ultrasound emitting members to the tissue via an acoustic coupling medium. By focusing the ultrasound energy at a specific target location, region, volume or area within the tissue, thermal effects can be confined to the specific location, region, volume or area, and such location, region, volume or area can be remote from the ultrasound emitting member.
With the use of high intensity focused ultrasound (HIFU), a discrete or defined target location, region, volume or area within a larger mass, body or area of anatomical tissue can be subjected to high intensity ultrasonic energy while surrounding non-target anatomical tissue is subjected to much lower intensity ultrasonic energy. In this manner, tissue at the target location, volume, region or area can be heated to a sufficiently high temperature so as to cause a desired thermal effect such as tissue damage, ablation, coagulation, denaturation, destruction or necrosis while tissue surrounding the target location, volume, region or area is not heated to damaging temperatures and, therefore, is preserved. Heating of the target location, volume, region or area, with the high intensity focused ultrasound, to an ablative temperature creates an ablative lesion in the tissue at the target location, volume, region or area that is subsequently naturally degraded and absorbed by the patient's body and is thusly eliminated such that the remaining body, mass or area of tissue is of smaller volume or size due to the absence of the ablated tissue.
The use of high intensity focused ultrasound to eliminate a target location, volume, region or area of tissue within a larger mass, body or area of anatomical tissue presents many advantages including minimization of trauma and pain for the patient, elimination of the need for a surgical incision, stitches and exposure of internal tissue, avoidance of damage to tissue other than that which is to be treated or removed, lack of a harmful cumulative effect from the ultrasound energy on the surrounding non-target tissue, reduction in treatment costs, elimination of the need in many cases for general anesthesia, reduction of the risk of infection and other complications, avoidance of blood loss, and the ability for high intensity focused ultrasound procedures to be performed in non-hospital sites and/or on an out-patient basis.
Various ultrasound treatment devices and/or methods for treating anatomical tissue with ultrasound have been proposed as represented by U.S. Pat. No. Re. 33,590 to Dory, No. 3,990,452 to Murry et al, No. 4,658,828 to Dory, No. 4,807,633 to Fry, No. 4,858,613 to Fry et al, No. 4,951,653 to Fry et al, No. 4,955,365 to Fry et al, No. 5,033,456 to Pell et al, No. 5,036,855 to Fry et al, No. 5,054,470 to Fry et al, No. 5,065,761 to Pell, No. 5,080,101 to Dory, No. 5,080,102 to Dory, No. 5,117,832 to Sanghvi et al, No. 5,134,988 to Pell et al, No. 5,143,074 to Dory, No. 5,150,711 to Dory, No. 5,150,712 to Dory, No. 5,158,070 to Dory, No. 5,222,501 to Ideker et al, No. 5,267,954 to Nita, 5,269,291 to Carter, 5,269,297 to Weng et al, 5,295,484 to Marcus et al, No. 5,304,115 to Pflueger et al, No. 5,312,328 to Nita et al, No. 5,318,014 to Carter, No. 5,342,292 to Nita et al, No. 5,354,258 to Dory, No. 5,380,274 to Nita, No. 5,391,197 to Burdette et al, No. 5,397,301 to Pflueger et al, No. 5,409,002 to Pell, No. 5,417,672 to Nita et al, No. 5,431,621 to Dory, No. 5,431,663 to Carter, No. 5,447,509 to Mills et al, No. 5,474,530 to Passafaro et al, No. 5,492,126 to Hennige et al, No. 5,501,655 to Rolt et al, No. 5,520,188 to Hennige et al, No. 5,542,917 to Nita et al, No. 5,620,479 to Diederich, No. 5,676,692 to Sanghvi et al, No. 5,728,094 to Edwards, No. 5,730,719 to Edwards, No. 5,733,315 to Burdette et al, No. 5,735,280 to Sherman et al, No. 5,738,114 to Edwards, No. 5,746,224 to Edwards, No. 5,762,066 to Law et al, No. 5,800,379 to Edwards, No. 5,800,429 to Edwards, No. 5,800,482 to Pomeranz et al, No. 5,807,308 to Edwards, No. 5,817,049 to Edwards, No. 5,823,197 to Edwards, No. 5,827,277 to Edwards, No. 5,843,077 to Edwards, No. 5,871,524 to Knowlton, No. 5,873,845 to Cline et al, No. 5,873,902 to Sanghvi et al, No. 5,879,349 to Edwards, No. 5,882,302 to Driscoll, Jr. et al, No. 5,895,356 to Andrus et al and No. 5,938,608 to Bieger et al.
In particular, focused ultrasound ablation devices used to thermally damage, ablate, coagulate, denature, cauterize, necrotize or destroy a target volume of tissue are exemplified by U.S. Pat. No. Re. 33,590 to Dory, No. 4,658,828 to Dory, No. 4,807,633 to Fry, No. 4,858,613 to Fry et al, No. 4,951,653 to Fry et al, No. 4,955,365 to Fry et al, No. 5,036,855 to Fry et al, No. 5,054,470 to Fry et al, No. 5,080,101 to Dory, No. 5,080,102 to Dory, No. 5,117,832 to Sanghvi et al, No. 5,143,074 to Dory, No. 5,150,711 to Dory, No. 5,150,712 to Dory, No. 5,295,484 to Marcus et al, No. 5,354,258 to Dory, No. 5,391,197 to Burdette et al, No. 5,431,621 to Dory, No. 5,492,126 to Hennige et al, No. 5,501,655 to Rolt et al, No. 5,520,188 to Hennige et al, No. 5,676,692 to Sanghvi et al, No. 5,733,315 to Burdette et al, No. 5,762,066 to Law et al, No. 5,871,524 to Knowlton, No. 5,873,845 to Cline et al, No. 5,873,902 to Sanghvi et al, No. 5,882,302 to Driscoll, Jr. et al, No. 5,895,356 to Andrus et al and No. 5,938,608 to Bieger et al. The focused ultrasound ablation devices are used to ablate various target areas in or on the bodies of patients including the brain, prostate, heart, urethra, blood vessels, deep seated tissue and tumors, liver, kidney, skin, breast, stomach and pancreas.
Ablation of anatomical tissue of the head and/or neck in order to reduce or eliminate such tissue in the treatment of various airway related disorders has also been proposed as illustrated by U.S. Pat. No. 5,423,812 to Ellman et al, Nos. 5,456,662, 5,514,131, 5,624,439, 5,674,191, 5,707,349, 5,718,702, 5,728,094, 5,730,719, 5,738,114, 5,743,870, 5,743,904, 5,746,224, 5,800,379, 5,800,429, 5,807,308, 5,817,049, 5,823,197, 5,827,277, 5,843,077 and 5,879,349 to Edwards and WO 97/43970. The areas ablated include the soft palate, uvula, tongue, tonsils, adenoids and turbinates. U.S. Pat. No. 5,423,812 relates to electrosurgical stripping of tissue. U.S. Pat. No. 5,456,662, No. 5,514,131, No. 5,624,439, No. 5,674,191, No. 5,707,349, No. 5,718,702, No. 5,728,094, No. 5,730,719, No. 5,738,114, No. 5,743,870, No. 5,743,904, No. 5,746,224, No. 5,800,379, No. 5,800,429, No. 5,807,308, No. 5,817,049, No. 5,823,197, No. 5,827,277, No. 5,843,077, No. 5,879,349 and WO97/43970 disclose RF ablation using tissue penetrating electrodes. U.S. Pat. No. 5,707,349, No. 5,728,094, No. 5,730,719, No. 5,738,114, No. 5,746,224, No. 5,800,379, No. 5,800,429, No. 5,807,308, No. 5,817,049, No. 5,823,197, No. 5,827,277, No. 5,843,077 and No. 5,879,349 refer to ultrasound as a possible source of ablative energy.
Prior focused ultrasound ablation devices typically have ultrasound emitting members, commonly including transducers, for emitting ultrasound energy and focusing the ultrasound energy at target areas in anatomical tissue in order to effect thermal ablation at the target areas. Exemplary focused ultrasound ablation devices employing transducers as the ultrasound emitting members thereof are disclosed in U.S. Pat. Nos. 4,658,828 to Dory, 4,858,613, 4,951,653, 4,955,365, 5,036,855 and 5,054,470 to Fry et al, 5,080,101 and 5,080,102 to Dory, 5,117,832 to Sanghvi et al, 5,143,074, 5,150,711 and 5,150,712 to Dory, 5,295,484 to Marcus et al, 5,354,258 to Dory, 5,391,197 to Burdette et al, 5,431,621 to Dory, 5,492,126 to Hennige et al, 5,501,655 to Rolt et al, 5,520,188 to Hennige et al, 5,676,692 to Sanghvi et al, 5,762,066 to Law et al, 5,873,845 to Cline et al, 5,873,902 to Sanghvi et al, 5,882,302 to Driscoll, Jr. et al, 5,895,356 to Andrus et al, 5,928,169 to Schätzle et al, 5,938,608 to Bieger et al and Re. 33,590 to Dory.
Some prior focused ultrasound ablation devices employ arrays or pluralities of transducer elements as the ultrasound emitting members, respectively, as represented by U.S. Pat. Nos. 4,658,828, 5,080,101, 5,080,102, 5,143,074, 5,150,712 and Re. 33,590 to Dory, 5,391,197 to Burdette et al, 5,501,655 to Rolt et al, 5,520,188 to Hennige et al, 5,928,169 to Schätzle et al and 5,938,608 to Bieger et al. U.S. Pat. Nos. 4,658,828, 5,080,101, 5,080,102, 5,150,712, 5,501,655, 5,520,188, 5,928,169, 5,938,608 and Re. 33,590 disclose the transducer elements as being actuated or driven in phase-offset relation to one another in order to change the location at which the ultrasound energy is focused in anatomical tissue. U.S. Pat. Nos. 5,746,224 and 5,800,429 to Edwards disclose an energy delivery device comprising one or more ring electrodes to which RF energy may be independently delivered to effect thermal ablation of tissue. Ultrasound is merely referred to as a possible source of ablative energy.
In order to enhance the efficacy of focused ultrasound ablation procedures, it would be desirable to customize or tailor lesions to be formed in particular patients. For example, it would be desirable for a single focused ultrasound ablation device to be capable of forming lesions of various sizes and/or configurations or patterns in anatomical tissue including lesions of various irregular or discontinuous patterns. Also, it would be desirable for a focused ultrasound ablation device to be capable of forming a lesion comprising disconnected lesion segments. By providing a focused ultrasound ablation device having the foregoing attributes, optimum lesion characteristics can be selected for particular patients based on assessments made by surgeons or other medical personnel at the time of surgery. However, prior focused ultrasound ablation devices, as exemplified by the above-mentioned patents, do not provide focused ultrasound emitting members having the foregoing attributes.